Data from: The genetic basis of discrete and quantitative colour variation in the polymorphic lizard, Ctenophorus decresii

Background: Colour polymorphic species provide invaluable insight into processes that generate and maintain intra-specific variation. Despite an increasing understanding of the genetic basis of discrete morphs, sources of colour variation within morphs remain poorly understood. Here we use the polymorphic tawny dragon lizard Ctenophorus decresii to test simple Mendelian models for the inheritance of discrete morphs, and to investigate the genetic basis of continuous variation among individuals across morphs. Males of this species express either orange, yellow, orange surrounded by yellow, or grey throats. Although four discrete morphs are recognised, the extent of orange and yellow varies greatly. We artificially elevated testosterone in F0 females and F1 juveniles to induce them to express the male throat colour polymorphism, and quantified colour variation across the pedigree. Results: Inheritance of discrete morphs in C. decresii best fit a model whereby two autosomal loci with complete dominance respectively determine the presence of orange and yellow. However, a single locus model with three co-dominant alleles for orange, yellow and grey could not be definitively rejected. Additionally, quantitative expression of the proportion of orange and yellow on the throat was strongly heritable (orange: h2 = 0.84 ± 0.14; yellow: h2 = 0.67 ± 0.19), with some evidence for covariance between the two. Conclusions: Our study supports the theoretical prediction that polymorphism should be governed by few genes of major effect, but implies broader genetic influence on variation in constituent morph traits.

背景：体色多态物种为探究物种内变异的产生与维持机制提供了极具价值的研究视角。尽管学界对离散体色形态的遗传基础已有愈发深入的认识，但同一形态内部的体色差异来源仍未得到充分阐释。本研究以多态棕龙蜥（Ctenophorus decresii）为研究对象，一方面检验离散形态遗传的经典孟德尔模型，另一方面探究不同形态个体间连续体色变异的遗传基础。该物种雄性喉部体色可分为四种类型：橙色、黄色、黄围橙色以及灰色。尽管目前已确认这四种离散形态，但橙色与黄色的占比仍存在显著差异。我们通过人工提升零代（F0）雌性与子一代（F1）幼体的睾酮（testosterone）水平，诱导其表现出雄性喉部体色多态性，并对整个谱系内的体色变异进行了量化分析。结果：棕龙蜥（C. decresii）离散形态的遗传模式最符合如下模型：两个具有完全显性效应的常染色体位点分别控制橙色与黄色体色的出现。不过，由三个共显性等位基因（分别对应橙色、黄色与灰色）控制的单位点模型，仍无法被完全排除。此外，喉部橙色与黄色占比的数量性状表达具有高度可遗传性（橙色：h²=0.84±0.14；黄色：h²=0.67±0.19），且二者间存在一定的遗传协变证据。结论：本研究证实了“多态性状由少数主效基因调控”的理论预测，但同时表明组成形态的性状变异受到更广泛的遗传影响。